1. Field of the Invention
This invention pertains to the mounting of a support frame for high-voltage electrodes in an electrostatic precipitator.
2. State of the Prior Art
In an electrostatic precipitator, an electrically conductive support frame for high-voltage electrodes is suspended from the roof of the precipitator by a number of mounting assemblies that carry the weight of the support frame and of the electrodes attached thereto. Each mounting assembly includes an electrical insulator to isolate the high-voltage support frame and electrodes from electrically grounded components of the precipitator.
In the prior art, each insulator for isolating the high-voltage support frame in an electrostatic precipitator from the roof of the precipitator had a surface directly exposed to a particulate-laden gas in the interior of the precipitator. Consequently, a layer of particulates (e.g., fly ash from a coal-fired burner), or a coating comprising a mixture of moisture and such particulates, tended to form on the surfaces of the high-voltage insulators. When such a coating developed to the point where a direct electrical path to ground was established on the surface of an insulator, the high-voltage electrodes would be electrically shorted. Failure of a few high-voltage insulators, or even one such insulator, in an electrostatic precipitator could cause serious reduction in particulate collection efficiency.
In the prior art, it was customary to supply heated air to the vicinity of each high-voltage insulator in an electrostatic precipitator in order to prevent the air adjacent the insulator from passing through a dew point, particularly during precipitator startup. In this way, the formation of moisture droplets in the vicinity of each insulator was inhibited. Typically, a single large blower would be used to move heated air through a network of thermally insulated piping to the vicinity of each of the insulators. Because of the long runs of piping required for the heated air to reach many of the high-voltage insulators, auxiliary heaters were often provided adjacent some or all of the insulators to prevent the heated air from being cooled to the dew point by winter weather conditions.
Prior art systems for delivering heated air to the individual high-voltage insulators in electrostatic precipitators were expensive because of the long runs of piping required. Furthermore, prior art systems for delivering heated air were generally unable to maintain a uniform distribution of heated air over the entire surface of each insulator. Thus, cool spots on which condensation could occur tended to develop on the high-voltage insulators in the prior art.